Field of Invention
The present invention mainly relates to the field of vehicular active safety design, and particularly relates to a method and a device for detecting the safety driving state of a driver.
Description of Related Arts
With the development of vehicle industry, vehicles have increasingly become an important part of social production and daily life; meanwhile, vehicle safety also gradually becomes a focus of attention. According to the statistics, about 75% of road traffic accidents are caused by human errors, namely caused by personal factors of drivers. Specifically, the personal factors include inaccurate estimation of drivers on vehicle running environments, response lag of drivers and the like. Thus, the safety of road traffic can be effectively improved by detecting whether the driving state of a driver is safe or not via technical means.
At present, the detection technologies for the safety driving states of drivers can be divided into three types: a detection method based on physical fatigue characteristics of a driver, a judgment method based on a running relation between a vehicle and a road, and a psychological response monitoring method based on stimulus-response monitoring.
The working principle of the detection method based on physical fatigue characteristics of a driver is based on a basic assumption: when the mental state of a driver is poor, the driving state is also poor, so the driver cannot safely accomplish the driving task. Generally, the physical fatigue characteristics capable of being used for detection include eye closing degree, brain wave, steering wheel holding strength and the like. Some practitioners published a driver fatigue detecting method based on monocular vision for judging the mental state of a driver by detecting the blinking frequency of the driver. This method includes the steps of installing a camera facing the face of the driver above a cab instrument panel, acquiring a driver face image by using the camera, performing face detection and tracking on each frame of the acquired image, performing eye detection and positioning within the detected face area, recognizing eye opening and closing states by using left and right eye areas, and finally performing fatigue detection via the detection states of continuous frames. Some other practitioners published a method and a system for detecting the mental state of a driver by continuously detecting abnormal shake of a driver head, wherein the working principle is to detect the shaking frequency and mode of the driver head by using a sensor installed at the headrest of the driver and then judge the mental state of the driver from the abnormal shaking mode. In conclusion, the method for deducing the safety driving state of the driver from the fatigue state of the driver has the problems of the following three aspects: I, the method is an indirect detection method with unreliable effect: it is difficult to give a direct corresponding relation between the fatigue state and the safety of the driving behavior of the driver by merely taking the fatigue state of the driver as the detection means of the safety driving state of the driver, and it is uncertain that fatigue is judged by external physical characteristics; II, deducing whether the driving state of the driver is safe or not from the fatigue state is limited to unsafe state detection: the driver in an unsafe driving state is not always in a fatigue state; and III, it is difficult to ensure the timeliness when whether the driving state of the driver is safe or not is deduced from the fatigue state is adopted: when the driver is in a fatigue state, the driving behavior is quite unsafe.
The working principle of the judgment method based on a running relation between a vehicle and a road is to forecast impending accidents such as collision by directly measuring the relations between the current vehicle and other vehicles and between the current vehicle and the road. Some practitioners published a lane departure reminding device based on a single chip, which detects the driving state of a driver via the abnormal lane-crossing driving action of a vehicle. The method has the defects of I, a judgment is generally given at an impending dangerous traffic accident; and II, it is difficult to definitely and objectively judge normal traffic accidents and abnormal traffic accidents, e.g., normal overtaking lane-crossing behavior and abnormal lane departure behavior.
The working principle of the detection method based on stimulus-response is to evaluate the psychological response of a driver by using a specific stimulation mode. Some practitioners recently published a method for detecting the mental state of a driver via a sight capturing technology. This method includes the steps of generating an artificial visual stimulus first, and then detecting whether the driver notices the stimulus or not by using the sight capturing technology, so as to evaluate the judging ability of the driver on the current emergency. The method can be used for directly judging whether the driver can make a response to the sudden stimulus or not, but has the following defects similarly: I, the attention of the driver is easily distracted; and II, the stimulus of the specific mode is additional for the psychological activity of the driver itself, so that the burden of the driver is increased.
With further studies on the causes of traffic accidents, people gradually notice that unsafe driving states of drivers are the main cause of traffic accidents. The unsafe driving states at least include two types: slow response caused by fatigue driving, and unreasonable distribution of attention of drivers in non-fatigue driving. For example, drivers have insufficient experience and poor driving habits, new learners are too tense and do not notice traffic accidents which should be noticed. For another example, drivers are attracted by other targets such as advertising boards and the like, read messages, are distracted and the like. The existing detection technologies for the safety driving state of a driver are difficult in detecting the second type of unsafe driving states.
Upon years of studies, people understand the relations between the sight direction (the direction of a fixation point relative to a driver) of a driver and road scenes and between the sight direction of the driver and road traffic accidents increasingly deeply. In the normal driving state, the driver should carry out reasonable attention distribution and conversion in different road scenes and road traffic accidents. If the driver cannot make a quick response to instant important traffic accidents, the driver is in a dangerous or abnormal driving state.